Add fromString method
#4
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The Data.Int.fromString equivalent for Number. Tests have been provided, as well as code documentation.
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Thanks you very much! This looks very good. I'll add a few inline comments. |
| -> Maybe Number | ||
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| -- | Attempt to parse a Number from a String using JavaScript's parseFloat. |
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We should probably specify when to expect a Nothing result here.
| return function (string) { | ||
| var result = parseFloat(string); | ||
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| return isNaN(result) ? nothing |
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I believe isNaN is not enough here, because parseFloat can also return Infinity (for inputs like 1e1000). isFinite would be a better choice, I think.
Thinking about this, it would be very cool to have isNaN and isFinite available in purescript-numbers. Then, fromString could also be implemented in PureScript.
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Agreed on Infinity, will amend now. Interestingly, PureScript's core libraries tend to take the stance that NaN/Infinity is "undefined" behaviour. I wonder what @paf31 would think of isNaN and isFinite existing in PS.
| test "invalid number string" do | ||
| assert "invalid strings are not coerced" $ | ||
| fromMaybe true $ false <$ fromString "bad string" | ||
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Thanks for adding tests, too! Could you also add a test for an input like 1e1000?
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Going to close this PR as I think that, aside from the edge checks, this is all already implemented in |
I knew that, but I thought that your version was still very useful.. precisely due to the checks. Something similar was also asked for in purescript-deprecated/purescript-globals#5
Hm, .. we could still use the unsafe
Yes, but there are situations where we cannot avoid getting |
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See purescript/purescript-integers#17 for another related discussion. |
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I went ahead, merged this and re-implemented it using the methods in Again, thank you very much! |
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Oh, wow! Sorry, I'd gone to bed, hah! No problem - thank you very much, too! |
Hello!
This is the
Numberequivalent ofData.Int.fromString. Hope this is ok! I've added tests to the suite, too.PS: I looked at the process of re-uploading packages, and, while I think I probably can do it, it would result in me being registered as the package uploader. Not quite sure what the repercussions are, so I'm going to run away and leave it to you. Probably being silly, but best to be safe.